Changes

The Garmin 620 has become rather notorious for its poor GPS quality. I raised the issue with Garmin support and they kindly sent me a replacement device, but as you can see below, the replacement was no better. In fact, it was is actually worse than my original unit. I've also broken down the readings by firmware version, and you can see some slight improvement going from V2.90 to V3.00, but it's only slight.

I have come to suspect that the 620 has two issues. Firstly, Garmin has compromised GPS accuracy for size and battery life. This is then compounded by high levels of smoothing in an attempt to compensate. SecondlyI'm told that the newer Garmin watches have changed from a SiRFstar chipset to a MediaTek chipset, though I suspect can't confirm this. I thought that the 620 has had a problem with its [http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System WAAS] processing. , but I have it on good authority that no Garmin Forerunner has WAAS provides an offset to GPS receivers to correct for errors, so an error in WASS processing could lead to the GPS location being offsetsupport. Below are a couple of examples where you can see that it appears that the track has been offset, rather than the 620 simply becoming 'lost', which I'd attributed to WAAS error.